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Rowan in Shaker Heights recently tested positive for COVID-19 after receiving a negative test result a few days ago. He asked: "How do you best use tests to avoid false negatives? Does vaccination make you more likely to get false negatives from any test?"

Dr. Christine Schmotzer, vice chairman of the University Hospital System Pathology, said there are several potential reasons for false negative test results.

She said that one of the biggest problems is timing. She said that if there is not enough virus in the sample, a person may have a negative test result, which may happen in the early stages of infection.

Schmotzer said that once a person develops symptoms, it is recommended that they be tested.

Schmotzer said: "Even if you have symptoms and the test result is negative, you may not have enough virus at the time." "We do recommend that if people test negative and show symptoms, then they talk to the doctor again... Retest within 1 to 2 days." 

She said that another factor that affects the accuracy of COVID-19 tests is the type of test. She said that PCR tests performed and analyzed in hospitals or laboratories are more accurate than quick home antigen tests, such as those that people buy in pharmacies.

"As the number of viruses decreases, PCR will become positive," Schmotzer said. "Compared with rapid antigen testing, the false negative [risk] of PCR testing is lower."

She added that the rapid test still helps to show whether someone has COVID-19 at a specific time and is most accurate when the person has symptoms.

Schmotzer said that another common cause of false negatives is personal error. She said that a person may not get a good enough sample on a nasal swab-so she recommends carefully reading the instructions for the home rapid test.

"You have to use very good quality cotton swabs," Schmotzer said. "The swab needs to be far enough in your nose to avoid discomfort."

She added that in terms of COVID-19 testing, guidance depends on the specific situation. She said that if a person has symptoms of COVID-19, they are usually advised to get tested as soon as possible.

She added that if the person is in close contact with someone who has tested positive for COVID-19, testing recommendations will vary depending on whether they are vaccinated.

She added that if individuals are not vaccinated, they are advised to be tested for COVID-19 immediately, but if they are fully vaccinated, they can be tested within 5 to 7 days after exposure to ensure peace of mind.  

The listener also asked whether vaccination would make people more likely to get false negatives. Schmotzer said this is unlikely to happen because studies have shown that they don’t spread the virus as much as people who have not been vaccinated.